LoginAuthUserView: Fix crash

Don't call NotifyAccessibilityEvent on the view being destroyed.

Bug: 1049414
Change-Id: I06c2a9b24a0f03a948582d9706ae4917e2301a7b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2057068Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Roman Aleksandrov <raleksandrov@google.com>
Cr-Commit-Position: refs/heads/master@{#741498}

ash/login/ui/login_auth_user_view.cc

@@ -138,6 +138,11 @@ ui::CallbackLayerAnimationObserver* BuildObserverToNotifyA11yLocationChanged(
   return new ui::CallbackLayerAnimationObserver(base::BindRepeating(
       [](views::View* view,
          const ui::CallbackLayerAnimationObserver& observer) {
+        // Don't notify a11y event if the animation is aborted, as |view| may no
+        // longer be valid.
+        if (observer.aborted_count())
+          return true;
+
         view->NotifyAccessibilityEvent(ax::mojom::Event::kLocationChanged,
                                        false /*send_native_event*/);
         return true;
@@ -150,6 +155,11 @@ ui::CallbackLayerAnimationObserver* BuildObserverToNotifyA11yLocationChanged(
   return new ui::CallbackLayerAnimationObserver(base::BindRepeating(
       [](LoginPinView* view,
          const ui::CallbackLayerAnimationObserver& observer) {
+        // Don't notify a11y event if the animation is aborted, as |view| may no
+        // longer be valid.
+        if (observer.aborted_count())
+          return true;
+
         view->NotifyAccessibilityLocationChanged();
         return true;
       },